The invention relates generally to an intake manifold for a combustion engine of the type comprising a dimensionally stable induction pipe body having at least one flow-through opening and at least one first adjusting element being arranged in the first flow-through opening to vary the cross-sectional area through which an air/fuel mixture can pass. This adjusting element typically is a throttle valve, which is rotatably supported in the induction pipe body and which is capable of being urged to sealingly engage with the boundary wall of the first flow-through opening.
Such types of intake manifolds are generally known. However, in many of the known intake manifolds, the engine output of the combustion engine is diminished by a return flow of air-fuel mixture from the combustion chamber back into the intake manifold. Because of piston travel and valve overlap, such a return flow in the intake manifold occurs with greater intensity in the low speed range, when the force of the gas flow is relatively small.
There remains a need for the further development of an intake manifold in which the air-fuel mixture is prevented from flowing back into the intake manifold of the combustion engine, and in which resistance to flow in the direction of the combustion engine is not significantly increased by the intake manifold at high engine speeds.